Davy Crockett Weapon System
The Davy Crockett Weapon System was a tactical nuclear launch system developed in the 1950s to launch the W54 nuclear warhead. The system had two types of smoothbore recoilless gun launchers. __TOC__ History The Davy Crockett was developed to counteract any Soviet invasion of Eastern Europe or North Korean invasion of the South. At the time it was made, there was little faith in the idea that armor alone could stop the massed Russian tank divisions, in particular since they were technologically superior to anything in Western service, or that South Korea could stop the vast forces of the North with conventional weapons alone. It was imagined that the relatively small crew-served recoilless gun launcher, while limited in range, would be much harder for the enemy to locate than the massive 83-ton M65 Atomic Cannons that previously had the same role, and would provide a low-power compliment to the kiloton-range MGR-1 Honest John and MGR-3 Little John unguided nuclear rockets. One of its strongest proponents was the West German Defense Minister Franz Josef Strauss, who argued that a single Davy Crockett would be equivalent to 40-50 volleys from a conventional artillery division, and thus the weapons would represent a large saving on procurement budgets for howitzers which could then be spent elsewhere. Other NATO figures were not fond of this argument, as such an arrangement would render an escalation to tactical nuclear weapons effectively mandatory. Test data for the system was mostly gathered by firing the spotting rifle or XM421 dummy warheads, with the actual warhead only being tested twice as part of the nuclear test sequence Operation Sunbeam at the Nevada Test Site. The first was Little Feller II, a static effects test of a W54 in Davy Crockett configuration suspended 3 feet above the ground, on July 7th, 1962. This gave a yield of 22 tons of TNT equivalent. The first and only firing of a complete Davy Crockett launcher with a real M338 warhead, Little Feller I, took place on July 17th 1962. The launcher was an M29, and the warhead was fired 1.7 miles (2.72 km), detonating at a height of 20-40 feet above the ground with yield equivalent to approximately 18 tons of TNT. The latter was the last atmospheric nuclear test carried out at the Nevada Test Site. The system was not well-liked by either politicians or commanders. Funding was provided for 6,247 guns of the two types, but only 2,100 were ever produced, issued at a rate of four launchers to a battalion. Just 400 M338 projectiles were made, making the Davy Crockett an odd case of a gun over five times more common than its own ammunition. The M28 launcher was seen as the most limited and after a while almost all launchers issued were M29s. Ultimately, all Davy Crockett launchers were withdrawn from service in 1971. Design details The two systems designed as launchers were the M28 and M29: the M28 was the lighter and easier to transport, while the M29 was built for range. Both were muzzle-loading smoothbore recoilless guns using a two-part propulsion system to handle launching their fairly fragile nuclear projectile. The launcher would either be carried in an APC and then set up and fired away from it on a tripod, or mounted on the back of an M38 or M151 jeep and fired without dismounting. The first part of the propulsion system was an explosive propelling cartridge. The M28 used one cartridge, the M92, which was about the size of an M72 LAW rocket launcher. The M29 used three separate charges, with the M76 and M94 being inserted first, followed by the M77. Once this was loaded, the firing cables could be unrolled from the rear of the launcher and linked to a triggering mechanism: the launcher had no trigger of its own. A transfer piston or spigot (M5 on the M28, M2 on the M29) was then inserted into the barrel, with the warhead fitted to it using a bayonet mount. The whole system functioned somewhat like a gigantic rifle grenade. The launcher has no sights and instead uses a spotting rifle mounted underneath it: on the M29 this was a 37mm gun located near the weapon's muzzle, while the M28's 20mm spotting rifle was located about halfway along the gun tube and had to use a depleted uranium bullet to properly match the ballistics of the warhead. Both appear to have been single-shot breech-loading weapons. Ammunition The M338 was the lowest-yield version of the W54 warhead, also used in the AIM-26 Falcon air-to-air missile and B54 Special Atomic Demolition Munition. It was also the lowest-yield nuclear weapon ever mass produced, and approaching the absolute lower output limit of a functional nuclear warhead. Its yield was equivalent to 10-20 tons of TNT in terms of explosive force (damaging to unreinforced structures within 500ft of the detonation) with the primary damage mechanism being ionising radiation (instantly incapacitating within 500ft and fatal within days to about 50% of infantry exposed within 1,000ft). Since the projectile had to incorporate the 10.75-inch diameter core of the W54, it was a very large and bulbous assembly, and also very heavy: the M338 alone weighed 76 lbs (34.5 kg) without the spigot attached. This gave the projectile poor aerodynamic properties, and both launchers were notoriously inaccurate when fired with weighted dummy warheads. Practice firings used the M390, which had identical ballistics but 16 pounds of Composition B explosive instead of a nuclear warhead. The dummy version, the M421, was used for drills. This duplicated all of the external controls of the M338, but only contained ballast to simulate the weight of the real warhead. The nose of this version is plastic and the fins replaceable, in order to make it easier to repair after test-firing. The warhead used a timer detonator, set using a dial on the base. If this was not set to at least 1 second (1,000 feet), the warhead would not be armed on launch. This was intended to ensure an airburst rather than act as a safety feature. The maximum timer setting was 50 seconds. A safe-arm switch is also present on the side. The M390 did not have a timer as it was impact-fuzed, instead having an arming pin attached to the nose. Illustrations of the M421 show a two-setting height-of-burst selector with "low" and "high" settings, though it is not particularly clear what function this had. The 20mm spotting rifle used a cartridge called the M101, while the 37mm version used the M415 or M446. All three of these were tracers with a pyrotechnic fill designed to produce a bright flash and puff of smoke on impact. References Category:Recoilless rifles